894
FXUS61 KLWX 200133
AFDLWX

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
933 PM EDT Sun May 19 2024

.SYNOPSIS...
Warming temperatures are expected Monday and Tuesday as high
pressure builds overhead. A strong cold front approaches from
the Midwest and Ohio River Valley Wednesday before crossing the
area Thursday. The front stalls to the south Friday before
lifting back into the region this weekend to bring additional
chances for showers and thunderstorms.

&&

.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
Upper trough axis is southeast of the area this evening while
surface high pressure noses southwestward from the Canadian
Maritimes. Skies have cleared across much of the area. The lone
shower in the highlands should dissipate in the next hour or
two. While surface winds will be light to calm, there will be a
marine influence to the low level airmass, especially east of
the mountains. In addition, soils are still wet from recent
rain. Therefore, expect low clouds and fog to develop during the
second half of the night. Latest guidance suggests low clouds
may prevail along the immediate I-95 corridor, with the highest
chance for dense fog just to the west along the Virginia
piedmont. Will have to monitor obs through the night since
probabilities don`t suggest high confidence at this time. Lows
will range from the mid 50s to near 60.

&&

.SHORT TERM /6 AM MONDAY MORNING THROUGH TUESDAY NIGHT/...
Monday begins our reprieve from unsettled conditions with dry
weather and sunny skies in the forecast as high pressure builds
in. High temperatures rise to the mid-upper 70s, starting a
warming trend through mid-week as well. Low clouds and fog from
Sunday night should burn off by late morning, hanging the
longest along the Chesapeake and Potomac. Clear skies and
lingering moisture likely yield patchy fog once again Monday
night into Tuesday morning. Low temperatures will be in the mid-
upper 50s.

Dry and sunny conditions continue through Tuesday, high pressure
remaining overhead but gradually sliding eastward. High
temperatures warm into the upper 70s to 80s. While not currently
forecasting fog Tuesday night, with dewpoints in the upper 50s
to low 60s, if we cool enough overnight some patchy fog could
develop, but it`s not looking as certain as Sunday and Monday
night.

&&

.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
Overall not much change in our current weather pattern over the last
few weeks. We still remain in the cycle of 1-2 days of sensible
weather followed by 2-3 days of unsettled conditions. Unfortunately,
as we head into the middle and latter half of the workweek the
unsettled weather looks to return.

Strong low pressure over the upper Great Lakes region and it`s
associated cold front draped across the Upper Midwest/Ohio River
Valley will gradually push east Wednesday as the upper level ridging
breaks down. 06z/12z guidance continues to slow the progress of the
front east Wednesday with most of the guidance favoring Thursday
into Thursday night. This is due in part to the placement of the
departing surface high off the NJ/Long Island coast and secondary
surface high pressure over the southern Appalachians region. Even
with that said, a few showers and thunderstorms (some of which could
be strong) remain possible in areas west of the Blue Ridge Wednesday
afternoon and evening as an initial piece of shortwave energy
pivoting around the upper level low passes through. Most locations
will remain dry with increased south to southwesterly winds boosting
temperatures into the mid to upper 80s to near 90 outside the
mountains/bay.

The cold front looks to push through the area Thursday into Thursday
night before stalling to the south Friday. Latest 12z guidance
suggest a frontal passage right during the peak heating period
Thursday mid to late afternoon. This will allow both CAPE and shear
to maximized lending to a potential severe weather threat. Right
now, the Storm Prediction Center makes a mention of this threat on
there Day 5 outlook. CSU Learning Machine Probabilities also
highlight areas along and east of the Blue Ridge (i.e I-95 corridor
in the 15-30 percent probabilities of severe thunderstorms) during
this timeframe. Multi-ensemble CAPE values range from 500-1000 J/kg
on Wednesday before rising into the 1000-1500 J/kg range by Thursday
afternoon. With the approach of the front, it remains to be seen if
the increasing vertical shear (35-45kt) can coincide with the higher
CAPE values. As a result, strong to severe thunderstorms remain
possible Thursday afternoon and evening. Some storms will be capable
of damaging winds and large hail given the antecedent conditions. As
for coverage, some uncertainty remains given any cloud cover early
on and the resultant timing of the front as it passes through. High
temperatures Thursday will once again be in the mid to upper 80s
with 70s over the mountains.

The front stalls south and east of the area Friday before retreating
back north into the start of the weekend. Additional shower and
thunderstorm chances are likely as a result although uncertainty
remains in the overall pattern. High pressure tries to briefly build
back into the area Sunday before another series of fronts impact the
area by the early part of next week.

&&

.AVIATION /02Z MONDAY THROUGH FRIDAY/...
Main concern for tonight revolves around low clouds and/or fog
during the second half of the night due to calm winds and moist
near-surface conditions. There`s somewhat of a signal for low
clouds (MVFR to IFR) to prevail at BWI/MTN/DCA, with higher
chances of fog to the west. Have continued to be somewhat
conservative in the TAFs due to uncertainty, but dense fog is
not out of the question at IAD/CHO/MRB.

Conditions should improve by late Monday morning. Afterwards,
dry and sunny conditions are expected through Tuesday with winds
remaining fairly light out of the S/SE.

A strong cold front will approach the region Wednesday before slowly
passing through Thursday into Friday. Some restrictions are possible
especially Thursday into Thursday night as the front crosses. This
is due in part to an increase in shower and thunderstorm activity
especially along and east of the Blue Ridge. The front stalls to the
south late Thursday into early Friday before retreating back to the
north to start the weekend. Additional restrictions are possible
during this time. South to southwest winds are expected Wednesday
into Thursday before shifting to the west and northwest Thursday
night into Friday.

&&

.MARINE...
No hazardous marine conditions are expected through Tuesday.
Winds remain fair, generally southeast or south. As winds turn
more southerly, some channeling is possible but is not currently
expected given the light flow.

Some SCA level southerly channeling is possible Wednesday into
Wednesday night ahead of an approaching cold front from the Ohio
River Valley. The cold front looks to slowly cross the waters
Thursday afternoon into Thursday evening bringing the risk of
showers and thunderstorms. Special Marine Warnings may be required
for the stronger storms. Winds shift to west-northwest behind the
front Friday as it stalls south of the waters.

&&

.TIDES/COASTAL FLOODING...
Water levels look to be stable or even rising a little over the
next few days with light southeast to south winds. More
sensitive locations such as Annapolis, Straits Pint, and DC
Waterfront will likely see minor tidal flooding during the
astronomically higher tide cycles. With tonight`s cycle being on
track, am issuing Coastal Flood Advisories for these locations.
Additional locations could see minor flooding over the next few
days.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...Coastal Flood Advisory from 4 AM to 9 AM EDT Monday for DCZ001.
MD...Coastal Flood Advisory from 2 AM to 7 AM EDT Monday for MDZ014.
     Coastal Flood Advisory until 2 AM EDT Monday for MDZ017.
VA...None.
WV...None.
MARINE...None.

&&

$$

SYNOPSIS...EST
NEAR TERM...ADS
SHORT TERM...CAS
LONG TERM...CAS/EST
AVIATION...ADS/CAS/EST
MARINE...ADS/CAS/EST
TIDES/COASTAL FLOODING...LWX